Free Shipping on all orders $35 and up.

We offer standard delivery in 3 business days or less.

Please see our shipping map below for estimated times.

Estimated standard delivery time to the U.S. and Puerto Rico

Delivery time estimates do not apply to large or heavy items that require special
shipping (including most TVs), items shipped directly from the manufacturer, or
out-of-stock items. Some items that ship from the manufacturer can only be delivered
to addresses within the 48 contiguous states.

Delivery time for standard shipping to any of the 50 U.S. states or Puerto Rico is 1-3 business days. Saturday, Sunday and national holidays are not considered business days for delivery purposes.

Factory-authorized dealer

Cable gauge chart

How to determine the best size wire for your amplifier's power and ground

Buck Pomerantz was born and raised in Philadelphia. His parents bought their first television set when he was born. He figured out how to run it by the time he was two. Besides athletics, his formative interests included electronics, amateur radio, music, and stage crew work. He got his BA in writing from Brown University. Then he joined a rock 'n roll band as their soundman and moved to Charlottesville, Virginia. After that venture failed, he spent time in Boston, New Orleans, and Berkeley. He worked in a music store in Austin manufacturing, installing, repairing, and operating sound systems for recording studios, clubs, and bands. He moved back to Charlottesville, ran a little recording studio and finally joined Crutchfield as a copywriter. He has 2 grown children and 3 grandchildren, but after a good nap he can still rock out.

In order to operate correctly, an amplifier needs its power and ground wiring to be large enough to accomodate its demand for electrical current. What gauge (thickness) wire to use for power cabling depends on how much current your system will try to consume, and on how long the wiring run will be.

The formula for current draw

To determine the approximate current draw (in amperes) of your amplifier (or amplifiers), you must first calculate the total power of the system (multiply the number of channels by the number of RMS watts per channel). If you have multiple amps, add up the total power figures to arrive at a grand total. Next, double your grand total power figure. Then, divide by 13.8.

Total RMS Wattage times 2 (Inverse of Amp Efficiency) divided by 13.8 Volts equals Current Draw in Amperes (explanation below)

The resulting figure is your system's approximate maximum current draw. Compare this number to the numbers in the "Amperes" column in the chart below. Cross-reference with the cable length (the distance from your battery to the amplifier's mounting location) to determine which gauge of cable you need.

Once you have estimated the total amperage of your system using the described formula, determine the proper power and ground wire gauge from this chart based on the length of power cable your installation requires. Please note that the smaller the gauge number, the larger the wire. 1/0 ("one-aught") is the common name for a 0-gauge wire; 2/0 ("two-aught") for a 00-gauge wire.

A more detailed explanation

Here is an explanation about the formula we use, in case you want more details. Calculating the amplifier's total power is straightforward, but the other two parts can be confusing.

No amplifier is 100% efficient

First of all, why do we double the total power figure? That's because the typical analog amplifier is about 50% efficient. That means about half of the power it generates is turned into audio output while the other half of the power is lost as heat.

So if your amplifier is putting out 400 watts, it's actually drawing about 800 watts of power from its source, and the amp's wiring needs to be big enough to handle that draw. (Class D amplifiers are much more efficient in comparison, but it's still safest to go with the larger wire size.)

Automotive voltage is neither 12 volts nor 14.4 volts

And the 13.8? Yes, vehicles have a 12-volt electrical system, but we're assuming that the vehicle is running — which means its alternator will bump up the system voltage to about 13.8 volts. This is a better real-world representation of the vehicle's electrical supply. Dividing by 12 results in a larger number, which could point to a larger wire gauge, but it's often in the same color range in the chart. Manufacturers use 14.4 volts, when they spec their gear, to exaggerate their power ratings.

Resistance increases with length

The reason different cable lengths bear different ratings is because the electrical resistance, inherent in all wire, builds up as the cable gets longer, until it forces the voltage to drop below a useable level. At that point, up-sizing the power cable will restore the voltage to its intended level.

Size matters for current flow

Finally, according to our tech support guys, the primary performance limitation in most amplifier installations is in the current delivery — either a weak ground or insufficient wire gauge. Installing too small of a wire gauge results in poor performance, potentially shorter service life of connected components (your amplifier and speakers), and a potential safety hazard.

On the other hand, installing too large a wire gauge doesn't really have any downside, and there is the potential for better performance. Obviously, there's no need to buy 2-gauge wiring when 10-gauge will do. That kind of overkill would be a waste of money. But if the chart could lean either way between two sizes, going with the larger wire size would be the smart choice.

Comments

Hector Perez from United States

how far I have to install my fuse to my amp?

Posted on 5/10/2015 9:37:09 AM

Buck Pomerantz from Crutchfield

Hector, The fuse in an amplifier's power cable should be installed as close to the battery as possible, within 6" ideally. In case of an accident, you do not want a live wire stretching throughout your vehicle - that could lead to a fire. Many people with multi-amp systems also fuse the individual power wires running to each amp. They most often do that with a fused power distribution block.

Posted on 5/11/2015 10:06:53 AM

gregory from jamaica

hey good day guys
i just check my system using the calculator and from what i am seeing is i will be drawing about 400+ amps. i had run 2 gauge wire from my battery to my distribution block and on the chat its saying i should have 0 gauge wire,, could i run another 2 gauge wire from the battery to the distribution block or do i have to change it out and get the 0 gauge

Posted on 5/13/2015 9:37:02 AM

Buck Pomerantz from Crutchfield

Gregory, I doubt any vehicle's electrical system will allow you to draw 400+ amperes from it without enhancements like extra batteries and a high-output alternator. This amount of current means your amplifiers are capable of 2,760+ watts RMS output. If this is truly the case, then even 1/0-gauge power and ground wires won't be large enough to safely pass this amount of power. I would suggest using 3/0-gauge (000-ga.) wire for this size application. Even two 2-gauge wires wouldn't be large enough for 400 amperes.

Posted on 5/14/2015 9:16:40 AM

Blake from Colorado

Great information here, but I am still not sure which gauge to use. I have an AudioBahn A4002T amp that will be going into a 97' Subaru Impreza Outback Sport. Its also about 14' long bumper to bumper so my length would prolly be much shorter than that.
The Amp's manual says this:
800 watts ACH Power
100 watts x2 @ 4 Ohms RMS Power
200 watts x2 @ 2 Ohms RMS Power
Also tho this website: [Link removed] said that it has an "Output Power / Total: 400 Watt" hence the confusion.
Could you clarify on what gauge I would most likely need?
Thanks,
Blake

Posted on 6/17/2015 2:01:29 PM

Buck Pomerantz from Crutchfield

Blake, This amplifier's power is right on the edge of two cable sizes, so it will depend on how you use the amp. If you want to drive two 4-ohm speakers: 100 watts RMS x 2 channels = 200 watts RMS total; 200x2/13.8 = 29 amperes; you'd need 10-gauge power and ground cables. If you want to drive two 2-ohm speakers, or want to bridge the amp to run a 4-ohm subwoofer; 400 watts RMS x 1 channel; 400x2/13.8 = 58 amperes; you'll want 8-gauge or 4-gauge wiring, depending on the length needed.

Posted on 6/17/2015 3:55:13 PM

mike johnson from champlin, MN.

I have installed a 500 watt amp that is 25 feet away from the CAP, it is driving two 12 inch subs and seems that i have installed the wrong power supply wire to the AMP can you help me? and do you have the wire size in stock? will need 30 feet

Posted on 6/22/2015 9:25:56 PM

Buck Pomerantz from Crutchfield

Mike, I'm not sure you need a capacitor for a 500-watt system, but a capacitor usually gets installed as close to the subwoofer amplifier as possible to be effective, not 25-feet away. 30 feet is awful long - is this an RV or bus? If you don't plan on ever expanding the system or your amplifier uses Class D amp technology, then 4-gauge power and ground wires will do. Otherwise, I'd use 2-gauge power and ground wiring. Crutchfield presently carries 4-gauge wire, but not 2-gauge.

Posted on 6/23/2015 11:14:52 AM

Joey from US

I made the mistake of buying a cheap walmart brand wire, I originally ran my 1600 watt amp with a 1200 watt power wire, but i sold the wire along with that jeep, So i put my 15" L7 and 1600 watt amp in my truck and thought i could skirt by on that, I just blew 3 fuses in the last 5 minutes, 2 80 amp 1 100 amp. I figure it to be the wire cause the amp works just fine... So what gauge wire should I be using?

Posted on 6/29/2015 10:46:14 AM

Buck Pomerantz from Crutchfield

Joey, Without knowing the specific model amplifier I can't be sure, but if your amplifier really is capable of putting out 1600 watts RMS of power (RMS not peak), according to this article's formula and chart it needs either 2-gauge or 1/0-gauge wiring, depending on the length. You'd also need a 200-amp to 250-amp fuse to protect your wire and vehicle from fire in the event of a short circuit.

Posted on 6/30/2015 10:52:15 AM

Ryan from missouri

Should you rate the wires from the distribution block to the amp separately? For example, If you have a two amplifier system pulling 91 amps with 12ft of cable you need 4-ga from the battery all the way up to the distribution block. Once you branch off, the amps are pulling 43 and 48 independently. At 4 feet does this mean it only requires two 10-ga wires?

Posted on 6/30/2015 2:17:13 PM

Buck Pomerantz from Crutchfield

Ryan, You are correct. Running a 12-foot 4-gauge wire from the battery ensures that all 91 amperes of current will arrive at the distribution block. Running a 4-foot 10-gauge wire for each amp will also guarantee adequate power flow to each amp.

Posted on 6/30/2015 4:24:58 PM

Dylan

Just to let you guys know... you have "+ 13.8" not "/ 13.8" written for your formula

Posted on 7/8/2015 9:02:00 AM

Buck Pomerantz from Crutchfield

Dylan, If you look a little closer at that symbol you should be able to see that it's an old-fashioned "divided by" sign - a horizontal line with a dot above and a dot below. Sorry if that's unclear.

Posted on 7/8/2015 10:40:20 AM

David B from Phoenix

I find it hard to believe the typo in the formula on the page. You might want to change the plus sign to a division sign ;)

Posted on 7/19/2015 8:14:16 PM

Buck Pomerantz from Crutchfield

David, Seeing as you are the second commenter who read that "divided by" sign as a plus symbol, I am going to rewrite the formula in English, with no mathematical symbols. This way, even if someone should read it on a small screen like a phone, there will be no misunderstanding. Thanks for pointing it out.

Posted on 7/20/2015 9:20:19 AM

neville from harare ( zim )

Good day I got a 8000 watt amp and two 2000 watt sub's my distance from batt is about 3 meters can I use a 0 gauge cable with a 3.2 farad capasitor.

Posted on 7/22/2015 4:09:37 AM

Buck Pomerantz from Crutchfield

Neville, I suspect that huge power rating you quote is a peak or maximum specification, which is useless for planning out a sound system. You should use RMS ratings only. Ten feet (3 m) of AWG 0-gauge wire (50 square mm) should be able to supply adequate current for a 2500 watts RMS amplifier.

Posted on 7/22/2015 2:36:12 PM

allen from lansing

Okay I have two amplifiers in my car. I have one 2000.2 autotek amp. 1000 watts per channel or bridged 2000 watts at 2 ohm steady. I went through a lot of problems thinking I had smaller wire because my protect was going off. Now I have 2 gauge lead power with 4 gauge ground. ( turned out a speaker was blown.
Second I have a old black lanzar 2100 optidrive competition and with a 45db boost. It is running bridged mono. That runs on same ground but a 6 gauge lead wire.
I want to get rid of wires. Can I run both the amplifiers on the same 2 gauge wire running to there full capacity even if I have to But a capacitor and if so what fared? I have been told by a friend if I run both on the same 2 gauge the wire will not handle both amps. I want to split the wire into a snake tongue to each amp.
I own a 2000 dodge neon manual 2.0l. The 2 gauge is 18 ft long.

Posted on 7/26/2015 12:32:33 PM

Buck Pomerantz from Crutchfield

Allen, I can get very little trustworthy information about your amplifiers, plus not knowing what you intend to run with them makes it difficult to give an exact answer. But I think running one 1/0-gauge power wire from your battery to a distribution block will work. From the distribution block you'll need to run 4-gauge power wires to each amp and 4-gauge ground wires from the amps to your chassis connection. If you think you need a capacitor, check out the 3.0 Farad model.

Posted on 7/27/2015 12:37:38 PM

Ryan from Louisiana

I have an amp and aftermarket door speakers that were already installed in my truck when i got it. No idea what brand, wattage, or impedance the speakers are. Amp is an outdated Alpine 4 channel that puts out 70rms/channel at 4 ohms and 100rms/channel at 2 ohms. I just ordered 2 P1 subs with 250rms and a 500rms amp that should push full power when wired at 2 ohms. My question is how do i tackle wiring these systems when I don't know what one really is but know exactly what I need for the other? And would it matter if the old amp is set at 4 ohms and the new one is 2? I know speakers of different impedance cant be hooked to the same amp but not sure if it matters that two amps are set differently

Posted on 7/28/2015 1:01:56 AM

Buck Pomerantz from Crutchfield

Ryan, Almost all aftermarket car speakers have a nominal impedance of 4 ohms. You don't set an amplifier to an impedance - you hook up a 4-ohm speaker to an amp, and voila: the amp is pushing a 4-ohm load. Rockford Fosgate P1 subwoofers come in SVC 4-ohm and SVC 2-ohm models. Not knowing which ones you have, or what amp you have make it impossible to give advice on how to wire them together. If you want a question answered about your system, you must identify your equipment by brand names and model numbers.

Free tech support for the lifetime of your product

I had to call for support on the evening of installation. Your tech helped me get going in minutes. It was good to be able to call at that hour, and nice to talk to someone who knew the problem immediately.

David, Customer

We want you to enjoy the items you purchase from Crutchfield

If you're not satisfied with your purchase, you may return items that are complete and like new for any reason within 60 days